textproduct: Albany

WHAT HAS CHANGED

A Flood Watch has been issued for this afternoon and evening for Dutchess and Ulster Counties for the potential for flash flooding due to excessive rainfall from thunderstorms. WPC continues a Slight Risk (Level 2 of 4) for Excessive Rainfall for much of this area.

For the convective threat, the Severe Outlook now has a Slight Risk (Level 2 of 5) for today across much of eastern New York and western New England. Damaging winds remain the main threat with any severe thunderstorms.

KEY MESSAGES

1) Scattered to numerous thunderstorms will develop this afternoon and evening across all of eastern New York and western New England. Some could be severe, with the potential for damaging wind gusts.

2) Thunderstorms this afternoon and evening will be capable of producing heavy downpours, which could result in flooding of urban and low lying areas, especially across Ulster and Dutchess Counties.

3) A few lingering showers or thunderstorms will continue into Friday for southern and eastern areas with the passage of a cold front, but no additional severe storms or flooding is expected on Friday. Seasonable and dry weather is expected over the weekend.

DISCUSSION

KEY MESSAGE 1...

An upper level disturbance is currently located over the Upper Great Lakes and it will be lifting across southern Ontario and into western Quebec for today. At the surface, a cold front is located well west of the area over the Ohio Valley and Midwest. Surface warm front will be lifting across the area this morning and a surface trough ahead of the main front will be approaching the area for this afternoon into this evening. This will be the focus for showers and thunderstorms, which look to develop by the early to mid afternoon hours.

There looks to be sufficient shear and instability for organized storms today. The 00z HRRR and 00z SPC HREF both shows instability should reach the 1000-2000 J/kg range, especially for southern areas. 0-6 km bulk shear should be around 30 kts today. As a result, storms look to organize into small bows or lines by late this afternoon into this evening, bringing a threat for straight-line wind damage. Some the stronger storms could contain some hail as well. An isolated tornado is possible for any supercells ahead of the main line and the 00z HRRR does suggest there may be enough low-level helicity, although Sig Tor parameters looks to max out around 1-2 today, mainly for eastern areas. AI/ML guidance continues to show the potential for damaging winds and an isolated tornado across the region for today as well and has been showing this signal for the past few days. SPC has expanded the Slight Risk (Level 2 of 5) and it now is in place for nearly the entire ALY Forecast area.

Storms may linger into the evening, but will start to diminish by midnight, as the best forcing shifts eastward and the loss of daytime heating allows instability to wane.

KEY MESSAGE 2...

In addition to the severe threat, there will be the potential for heavy rainfall and localized flooding this afternoon into this evening. PWAT values will be surging to 1.50 to 2.00 inches for this afternoon and evening thanks to the low-level southerly flow in place. Dewpoints will be reaching well into the 60s to near 70 by late this afternoon, so there will be plenty of moisture available. Rainfall rates can easily reach 1-2 inches per hour in this type of environment.

CAMs suggests that several rounds of storms are possible and some areas may see training of precipitation. Some of the CAMs (especially the RRFS) suggests that localized rainfall totals may exceed 4 inches. While the placement has varied somewhat from run-to-run, the consensus in ensembles seems to suggest that southern areas (Ulster and Dutchess Counties) may have the highest potential for heavy rainfall, as cellular activity may occur in addition to a main line of storms. As a result, have issued a Flood Watch for the potential for flash flooding for Ulster and Dutchess Counties, which also matches up with the Slight Risk (Level 2 of 4) for Excessive Rainfall from WPC. Urban and low lying areas would be the most susceptible to flooding, which may result in damaged and impassable roadways. As always, travelers are reminder to need cross flooded roadways.

In addition to southern areas, other parts of the area may still see flooding rainfall and some guidance does suggest parts of the Lake George Region and southern VT could see repeated downpours as well, so will need to monitor trends and possibly expand the current Watch further north.

KEY MESSAGE 3...

The storm's main cold front will be crossing on Friday. A few additional showers or thunderstorms are possible on Friday, mainly for southern and eastern areas, but coverage will be lower than Thursday. There won't be as much instability and shear, so storms won't be able to become severe and probably won't be widespread enough to cause any additional flooding. The threat for additional precipitation will end from west to east during the afternoon hours with the passage of the cold front.

Over the weekend, high pressure will allow for dry weather and seasonable conditions. Plenty of sunshine is expected on Saturday with highs in valley areas in the upper 70s to low 80s. Dewpoints will be more comfortable compared to recent days, with values in the 50s to low 60s. It will turn slightly more humid and warmer on Sunday, but it looks to stay dry with a partly sunny sky and highs reaching the lower to middle 80s.

AVIATION /06Z THURSDAY THROUGH MONDAY/

Through 06Z Friday... Mainly VFR conditions and light winds prevail at all terminals early this morning except for KGFL, which will continue to see periods of IFR vis/cigs due to mist and fog development throughout the early morning hours of Thursday. Conditions will improve by daybreak, with southerly winds beginning to strengthen at all terminals late this morning and becoming gusty. Scattered rain showers will begin to develop in the early afternoon hours, which could yield brief periods of MVFR conditions, particularly at KPOU and KPSF.

There is still uncertainty regarding the exact timing and coverage of rain and thunderstorms throughout the afternoon and evening, reflected by PROB30 groups at all terminals from 18-19Z through 00Z Friday. Any strong thunderstorm could bring brief periods of MVFR/IFR conditions, along with strong and variable gusty winds. Convection and gusty winds will begin to wind down towards sunset, leaving behind widespread MVFR cigs and some scattered showers at KPOU and KPSF through the end of the TAF period.

Outlook...

Friday Night: No Operational Impact. NO SIG WX. Saturday: No Operational Impact. NO SIG WX. Saturday Night: No Operational Impact. NO SIG WX. Sunday: No Operational Impact. NO SIG WX. Sunday Night: Low Operational Impact. Slight Chance of SHRA. Monday: Low Operational Impact. Slight Chance of SHRA. Monday Night: Moderate Operational Impact. Chance of SHRA. Tuesday: Moderate Operational Impact. Chance of SHRA...TSRA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...Flood Watch from noon EDT today through this evening for NYZ063>066. MA...None. VT...None.